"Tempera in questa aqua": Experimenting with Impact of Medieval Quenching Recipes on Steel Hardness: Pt 1 Text

Title Page for Lecture presentation

EMILY This presentation is based on a chapter we’re writing about the ways in which early modern people combined interests in alchemy and the secrets of nature with inspiration from popular literature to attempt to amend their armor and arms for improved success in battle. The chapter is based on the occasional presence of recipes in both manuscript and printed books of secrets and other recipes for improving arms and armor. These recipes often require re-tempering steel in order to imbue it with properties such as being rust-proof, extremely shiny, and impermeable to other weapons. Whether these recipes were used, how frequently, to what effect, and in what kinds of spaces are questions that lead us to new avenues for understanding what kind of impact people felt they could have on military outcomes. They also connect with many works of literature from the same era that presented fantastical heroes and villains wearing magical armor and wielding powerful weapons. We think these recipes are evidence of the ways that people actualized imagination, taking what they knew from literature and alchemical theory, putting it into practice to affect their lived experience of warfare. We’re doing this work in partnership with The Oakeshott Institute and Arms & Armor, and we’re excited to share some initial reflections on our first experiments. 

Armor enjoyed a ubiquitous presence in the 16th and 17th centuries. Popular literary works such as Matteo Boiardo’s late 15th-century Orlando innamorato and Ludovico Ariosto’s 16th-century Orlando furioso dazzled readers with magical, impermeable armor, and authors of both printed and manuscript books of secrets recorded instructions for how to produce actual armor with similar qualities. Considering that 16th-18th century Europe was in a constant state of war, it is not surprising that authors were preoccupied with ensuring the strength and impermeability of their armor. At the same time as people likely assigned the task of armor maintenance to blacksmiths or armorers, they also searched for ways to address a variety of vulnerabilities of armor common to both the popular romances and these recipe texts. They also turned to books of secrets for advice to simply make their armor more beautiful and personalized by adding precious metals and other decorations. 

Images of text used by research.

In our work, we combine approaches from scholarship of material culture and literature to approach armor and arms in a new way, considering how people’s everyday experimentation and domestic research was contextualized by popular literature and military experience. We argue that this pairing of these seemingly unlikely bedfellows of popular romance and domestic recipes not only replicates the kind of interdisciplinarity natural to the premodern writer and thinker, but it also literalizes anxieties about bodily vulnerability and, more importantly, attempts to take control of a chaotic environment by willing more protective armor and more powerful weapons into existence through recipes and the work of experimentation, research, and imagination. 

The early modern household, as many scholars have shown, was a critical site for scientific experimentation. From the palaces of rulers and the nobility to the humble homes of other folks, in both dedicated laboratories and multi-use kitchens, the natural world could be opened up by those who wanted to understand its secrets. In Italy especially, books of secrets were an extraordinarily popular genre of both printed and manuscript text, read by the nobility and the literate masses in an effort to understand some of these secrets of nature. These volumes usually included some alchemical information, whether theory or recipes, or both, that encouraged readers to engage in experimentation that was transformative in nature. Across scholarship on alchemy and books of secrets in Europe in this era, we have found few studies that include information about the recipes in these volumes that deal with transforming arms and armor on a small scale in the home. While there are usually only a handful of these arms and armor recipes in each volume, their frequent presence speaks to the interest that they held for both authors and readers.


Both Boiardo and Ariosto describe the armor worn by their numerous characters, most of which is enchanted or charmed in some way. Given how common the experience of war was in the early modern period, the prevalence of this magic or special armor is more than just a continuation of a medieval trope; it is also an expression of a fervent desire for better protection in a violent world. We turn first to luminous or shiny armor as proof against vulnerability. The most famous armor in both Orlando innamorato and Orlando furioso is Hector’s armor. Hector symbolizes the classical, masculine warrior ideal. We are first introduced to it in Orlando innamorato when Mandricardo, the king of Tartary, acquires the armor of Hector as a result of a quest. The shield prominently features Hector’s symbol of the white eagle along with an inscribed warning: “If you are not another Hector, do not touch me. He owned me. Earth has not his peer.” Hector’s status and reputation imbue his armor with its own promise and strength for the wearer, and via the inscription, the armor literalizes the connection between that classical hero and the next wearer. If only “un altro” Hector is worthy of wearing it, then the armor will transfer Hector’s reputation to the new wearer, announcing him (or her) as equally peerless.

Mandricardo succeeds in taking the shield and finding and taking the rest of Hector’s armor. In Orlando furioso he is killed by Ruggiero in a battle over rightfulness to display Hector’s symbol of the white eagle. Ruggiero claims the symbol by right of ancestry, and Mandricardo by right of possession of the armor (xxvi.99). Ruggiero then wears the helmet after taking the armor from Mandricardo (xxxviii.78). In this complicated transfer of armor, its chief value lies in its connection to the classical hero Hector and in the innate qualities of the magic armor itself. One of those qualities is its appearance: “The plates were luminous and burnished so bright, that it smarted the eye to see them.” The armor’s visual threat alluded to the power of the material itself. The eyes suffer seeing the bright armor, just as the potential enemies who oppose the wearer of this armor will suffer at his or her hands on the battlefield. The threat both here and in the inscription on the shield draws on the protective function of armor and deploys it offensively. Boiardo and Ariosto scatter numerous descriptions of shiny, bright armor throughout their romances, consistently identifying strong, usually enchanted armor as luminous.

Death of Brandimarte

Recipes for making luminous, rust-proof, and very strong armor abound in books of secrets. The entries are sometimes dedicated to each goal individually, but they are often combined, pointing to the interrelated importance of all three qualities in the production and maintenance of quality arms and armor. Indeed, modern sword and armor makers know that metal that is intended to be shiny, but has a cloudy film over it is at risk of degradation and rusting, and rust is a serious threat to the structural integrity of metal. Thus, bright armor and weapons were likely seen as critical for soldiers if they hoped to be as protected as possible. A few examples include: Gabriele Falloppio’s 1664 Secreti Diversi includes a recipe titled, “To distill iron & make it very strong, & white like silver,” and another titled “To make iron very strong, & beautiful like silver.” The 1529 Opera nuova intitolata dificio de ricetti has one entry titled, “To make arms polished & keep them shiny always,” and a recipe simply “To keep arms polished.” In a similar vein, an author named Canali included a recipe “to defend arms, & other iron from rust, & conserve their luster.” Two entries in Wellcome Library MS 739 are titled, “Arms that Stay Luminous.” The first uses vinegar and rock alum. The second is somewhat more complex and specific, and uses plant ingredients along with Greek pitch. All of these recipes point to the interconnection of strong arms and armor with brightness and cleanliness.

The connection between rusty, tarnished armor and death made in Orlando furioso is a striking example of why recipes like these may have been attractive to readers. Orlando, along with the heroes Brandimarte and Oliviero, are in Africa after Orlando has recovered from his madness. None of them have their customary armor, but they are going to battle several Saracen enemies they have previously fought with so need to find something. Orlando “brought together whatever he could, even what was rusty and burnished.” The word “brunito” is worth pausing on here because burnishing something makes it shine when done purposefully, but when the color is a result of corrosion or rust, that shine diminishes, leaving a visual marker of the quality of the metal. The lack of luster foreshadows the outcome of the encounter. Orlando, who like Achilles has almost completely impenetrable skin and doesn’t even need the armor he wears, and Oliviero survive because of Orlando’s skin and the fact that they find Orlando’s magic armor in a shipwreck and Orlando lets Oliviero wear it. Brandimarte, though, has only the rusty armor and is slain in the encounter when a two-handed sword blow breaks his helmet. Before this final blow, the description of the battle makes multiple references to his weak armor. He feels weak because of the armor: “feeling himself poorly armored.” Notably, Brandimarte is the only famous Christian hero who dies in either romance, so this death stands out, especially because of its connection to his rusty, lackluster armor.

AMANDA In addition to recipes for shiny armor, there are also numerous recipes for hardening armor and weapons. We partnered with Arms & Armor and The Oakeshott Institute to conduct an experiment on heat treatment of simple 1050 steel using a recipe from Caterina Sforza’s collection from around 1490 and one from the “On hardening” section of manuscript 3227a, which is roughly contemporaneous to Sforza’s collection. 3227a or the pseudo-Dohbringer is a German commonplace book collection primarily focused on fencing texts. It is sometimes attributed to Hans Dohbringer, who is actually one of four authors of an addendum on Liechtenauer’s art of longsword fencing. We selected these two texts as our sources for several reasons: 1) the military nature of Sforza’s recipe in a collection known to be authored by a woman pairs well with the explicitly martial intent of 3227a, which continues to be used today as one of the primary sources for learning Historical European Martial Arts (HEMA). 2) The selected recipes are representative of the “genre” of recipes for hardening iron or steel. 3) Both contain elements that are likely to actually contribute to the hardening of iron or steel. For the sake of time, we aren’t going to read the recipes aloud, but they’re up on the slide here. 

Text of Sforsza recipe

MS 3227aRecipe Text

Carbon is a necessary element for the hardening of iron. Both of these recipes provide an ample source of that whether from the worms, vegetable matter, or buck’s blood. For the Sforza recipe and the direction to “make water with them with an alembic,” we discussed whether to use alcohol or oil. We asked Craig Johnson, master bladesmith at Arms and Armor and expert in historical edged weapons, which process would be most likely for the desired outcome of hardening metal. He pointed out that the flammability of alcohol would make it unfit as a key component of a quenching liquid. Further, as he pointed out, a supply of alcohol around a bunch of smiths is unlikely to stick around long enough to be used for quenching. Further, oil is a common quenching liquid either alone or as a component in quenching recipes, so we added some canola oil to the Sforza recipe. Preparing the Sforza recipe included boiling earthworms in water to produce a water infused with earthworms. Leeks were processed with a small amount of water, as were radishes. One cup each of the worm water, leek water, and radish water were combined and boiled together to reduce. This liquid was cooled and combined with some canola oil and used for the quench. A second point to note about the Sforza recipe is that it calls for the maker to “tempera in questa aqua doi volte” (temper it in this water two times).Tempering twice is an interrupted quench and is a common practice by metal workers. 400-500 degrees °F is where most tempering happens, so in this process, the heated metal would be quenched and then pulled out at about that temp so as not to quench to full hardness. This allows the metal to cool down as it draws the heat from the unquenched part of the metal and offset brittleness.


The preparation process for the 3227a recipe was more involved. First, we needed the blood of a rutting buck. Fortunately, we live in Minnesota and know some hunters so we got some buck’s blood this fall and froze it. The next slides are a little gross because we show the blood and pureed worms, so you are welcome to look away if that feels more comfortable to you. Earthworms used to make the worm water for the Sforza recipe were then processed and 75 g of pureed earthworm was added to 75 g of pureed mealworms (equivalent to cockchafer grubs), 75 g of pureed radish, 75 g of pureed horseradish, and 75 g of buck’s blood. After thoroughly mixing the ingredients, the liquid was strained using cheesecloth.

Ingredients mashed

The beginning of “On hardening” also says cold water can be used to harden iron. This is another common quenching liquid so we used 5 samples of 1050 steel. Sample 1 is untreated. Sample 2 was treated using Sforza’s recipe. Sample 3 was treated with the 3227a recipe. Sample 4 was treated with cold water. Sample 5 was treated with canola or rapeseed oil, which is what is commonly used today, including by the bladesmiths at Arms and Armor. The forge was at approximately 1550 °F. The phase shift when the metallic matrix starts to melt happens around 500 °F, which is an achievable temperature in a coal forge or even late medieval or early modern home oven. This video compilation shows the quench for the 4 treated samples

MS 3227a ingredient prep

According to Craig, all samples showed evidence of hardening. He found the 3227a hardening and the appearance of the sample particularly interesting because of the similarity in substance coated on the surface and quality of steel underneath compared to when he uses a product called “Keepbryte Acti-Scale Compound.” This reddish material is a coating applied at about 300 °F and then the piece is heated to quenching heat. It stops the black scale from forming so a polished surface stays closer to a useable finish. It reduces effort to get the heat-treated surface clean. Compared to the Sforza recipe, the sample using the 3227a recipe would be much easier to clean to a polished appearance. 

Tested samples

Our next steps with this research included partnering with Nathan Mara and his students Cuong Ho and Mauricio De Leo in Materials Science and Engineering at University of Minnesota, to do Rockwell tests on the samples. A Rockwell test evaluates the resistance to abrasion or hardness of metal. Historians and metallurgists have analyzes numerous historical pieces of arms and armor and demonstrate ranges of hardness and steel quality. Most noteworthy is Alan Williams’ masterful study The Knight and the Blast Furnace: A History of the Metallurgy of Armour in the Middle Ages & the Early Modern Period. Williams’ works shows the skills that premodern armorers and blade smiths possessed, and our small experiments help contribute by showing that even using recipes available to the more common premodern person, steel could be hardened and treated using available materials and tools, even in the home.

Our goal for these “experiments” themselves is not really to attempt to methodically reproduce particular recipes or metallurgical practices, nor are we attempting to answer the question of “did the recipes work?” Instead, we are seeking to approach embodied knowledge production from the perspective of “what could these recipes potentially do? And why might people have tried or wanted to try out the recipes they collected?” It is for this reason that we bring together the recipe collections, popular literature, and technical treatises in the way that we do. Brandimarte could not have been the only premodern warrior (fictional or real) who felt himself poorly armored, and while he had no recourse to Sforza’s worm juice cocktail or 3227a’s rutting buck’s blood concoction, the wealth of recipes for treating, hardening, or otherwise improving arms and armor testify to the affective appeal of something like a home remedy that could make one feel less vulnerable. Our collaboration with Arms & Armor, Oakeshott Institute, and other colleagues highlights the importance of approaching embodied knowledge production not as a static set of practices, but as a dynamic and evolving process shaped by social, cultural, and material factors. 

Now, we’re really happy to turn things over to Nathan and Q who will talk about their research and further experiments with the quenched steel!

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